The present invention relates generally to image guidance for minimally invasive surgery and, more particularly, to augmented reality visualization using endoscopes.
Minimally invasive surgery is becoming increasingly widespread due to the benefits to both the patient (i.e., decreased morbidity and faster recovery) as well as the benefits to the insurance industry (i.e., less hospitalization time and lower cost). Typically, minimally invasive surgery involves creating one or more small incisions and performing any surgical tasks through those incisions using specialized, frequently elongated, surgical tools.
As one skilled in the art will recognize, visual feedback is essential to such minimally invasive surgery. Typically, visual feedback in such surgery is obtained via an endoscope, which is an optical or optoelectronic viewing instrument that is inserted into a patient's body to provide a local view of the surgical site. As one skilled in the art will recognize, an endoscope is a small, flexible or rigid tube capable of imaging an area inside a patient's body via a lens connected to or integrated with the end of the tube. Light is delivered to the area to be imaged, for example, via one or more optical fibers within the tube. This light is reflected off of surfaces within the body and is focused by the lens onto the one or more optical fibers and delivered to a display in, for example, an operating room. Many different types of endoscopes have been developed for use in different surgical procedures. For example, flexible endoscopes are used for surgeries in the ear-nose-throat and gastrointestinal fields. Specialized flexible endoscopes, called bronchoscopes, are used for procedures in the bronchial tree of lungs. Rigid endoscopes are used in other types of procedures. For example, rigid endoscopes called laparoscopes and thoracoscopes are used in surgeries of the abdomen and thorax, respectively. The resulting images from such endoscopes are used by a surgeon to, for example, accurately position surgical instruments or to diagnose various conditions. The accuracy of position of the endoscope as well as the surgical instruments becomes increasingly important as the difficulty and delicacy of a procedure increases.
For example, positioning and visualization of an endoscope and surgical instruments is critical in surgical procedures such as minimally-invasive thoracoscopic spine surgery. The goal of such surgery is typically to remove a damaged disc between vertebrae or to fuse vertebrae by filling a gap between vertebrae with bony material which, over time, grows together with the vertebrae. Performing such spinal surgery without opening a patient's chest and, instead, using minimally invasive surgical techniques, poses several challenges. First, guiding instruments such as a thoracoscope to a specific vertebrae is difficult since a physician cannot simply count vertebrae along the spine from inside the thorax. Second, the thoracoscope's field of view is somewhat limited and, therefore, it is difficult to judge depth of penetration from only the endoscope's image. Success of the procedure, however, is highly reliant upon accurate three-dimensional positioning of the endoscope and manipulation of the surgical instruments in order to prevent potential damage to the spinal cord.
Recently, in some attempts to increase the information available to surgeons, visual information from an endoscope has been combined with virtual information, for example derived from a Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) image collected prior to an operation. For example, in one such attempt, optical images from an endoscope were shown side by side on a display in the operating room with matching virtual images derived from such CT/MRI images. Thus, illustratively, a physician could see both a virtual and optical image of an area inside a patient's body and then, for example, the physician could manipulate the virtual display to “view” behind a structure or obstruction in the body. However, while this method provides added benefit over the use of an endoscope alone, it does not significantly add to the ability of navigating an endoscope in more difficult and delicate procedures.
In another attempt, virtual images of a patient's internal anatomy obtained via CT/MRI scanning are mapped to an actual image of the patient. Views produced by such a procedure are referred to herein and are known in the art as augmented reality views. In creating such an augmented reality view, the virtual images are registered to a patient coordinate system, represented by markers attached to the patient. A pointer, the position of which is tracked in reference to the patient coordinate system, can then be visualized in the context of the imaging system so that a user can look at a display and see a model of the pointer in relationship to the anatomical structures of the medical image. However, this method only uses the virtual images and the location of a pointer with no endoscopic or other local images. Therefore, such a method is not sufficient for the aforementioned delicate or difficult procedures.